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Biomedical subjects

M Crane

Publications and source records attributed to M Crane.

At least 55 records · Page 3Linked to original sources
PubMed2001

Effect of short-term exposure to chlorpyrifos on developmental parameters and biochemical biomarkers in Chironomus riparius Meigen.

Chironomus riparius Meigen were exposed to sediment spiked with 0, 0.01, 0.05, and 0.10 mg chlorpyrifos/kg dry sediment for 48 h as late third-instar larvae. Acetylcholinesterase activity, glutathione-S-transferase activity, burrowing behavior, emergence time, and adult dry weight were measured to determine which were the most sensitive biomarkers of exposure and effect for short-term sublethal exposures. There was a significant drop in acetylcholinesterase activity at the two highest concentrations, but no effect on glutathione-S-transferase activity. Behavioral and life history biomarkers were sensitive only to the highest concentration of chlorpyrifos. The association of life history changes (female weight and male emergence times) with a significant inhibition of acetylcholinesterase activity suggests that this can be used as a biomarker of exposure and effect.

Acetylcholinesterase↗
PubMed2001

The test-retest reliability of a new occupational risk factor questionnaire for outcome studies of low back pain.

This study reports the test-retest reliability of a 25-item occupational risk factor questionnaire that can be self-administered in clinical settings and used in outcome studies of low back pain or return to work programs. Subjects were 24 patients (workers on sick leave due to acute low back pain), 29 co-workers on active duty in the same jobs in a utility company, and 53 supervisors. Eighty-six subjects were re-tested within a mean interval of 7-10 days; one group of 20 supervisors was re-tested within 81 days. The questionnaire was self-administered during individual interviews. Reliability was estimated by the kappa statistic as the agreement on the scores within the raters in each group. The agreement ranged from 'slight' (0.15) to 'almost perfect' (0.93) when the re-test interval was less than 43 days. Patients and non-patients were consistent in their assessment of the job demands. rights reserved.

Disability Evaluation↗
PubMed2001

Toxicity of cadmium and zinc to Diplostomum spathaceum (Trematoda: Diplostomidae) cercarial survival.

The toxicity of cadmium and zinc at concentrations ranging from 0.1 to 10000 microg/l was investigated with cercariae of Diplostomum spathaceum at three temperatures (12, 20, 25 degrees C) and three levels of water hardness (distilled water, soft water, hard water). Under most environmental conditions survival of cercariae was reduced by increasing metal concentration. Increasing water hardness and decreasing water temperature caused an increase in the survival of both control and metal exposed cercariae. However, with decreasing temperature increased survival of metal-exposed cercariae above the control occurred at a number of low metal concentrations. Differences in the relative toxicity of cadmium and zinc to cercariae was dependent on the environmental conditions of exposure. The two heavy metals demonstrated little toxicity to cercariae during the period of maximum cercarial infectivity (0-5 h). The mechanisms of metal toxicity and their effects on cercarial survival are discussed.

Animals↗
PubMed2001

Can saltwater toxicity be predicted from freshwater data?

The regulation of substances discharged to estuarine and coastal environments relies upon data derived from ecotoxicity tests. Most such data are generated for freshwater rather than saltwater species. If freshwater toxicity data are related to saltwater toxic effects in a systematic and predictable way, the former can be used to predict the latter. This would have economic advantages due to a reduction in toxicity testing of saltwater species. If toxicity data are plotted as species sensitivity distributions, four theoretical relationships between freshwater and saltwater can be envisaged. Examples show that each one of these relationships is supported by empirical data. These examples show that although there is considerable potential for freshwater to saltwater prediction, species parity and representativeness need to be examined for each chemical substance to avoid bias.

Animals↗
PubMed2001

Short-term exposure to sub-lethal doses of lindane affects developmental parameters in Chironomus riparius Meigen, but has no effect on larval glutathione-S-transferase activity.

Chironomus riparius Meigen were exposed to 0, 0.01, 0.1, 0.5, 0.75 and 1.0 ppm lindane for 48 h as fourth instar larvae. Exposure had no effect on glutathione-S-transferase (GST) activity in larvae snap-frozen immediately following exposure. In contrast, exposure had longer-term consequences affecting developmental parameters. Concentrations above 0.5 ppm lindane affected larval behaviour, reduced adult body size and fecundity and delayed emergence times. The lack of significant change in GST activity when life history characters were affected by high concentrations of lindane, suggests that in C. riparius, GST is not a sensitive biomarker of pesticide exposure or effect.

Animals↗
PubMed2001

Toxicity of cadmium and zinc to miracidia of Schistosoma mansoni.

The specific objectives of this study were to elucidate metal toxicity to hatching, survival and avoidance behaviour of Schistosoma mansoni miracidia. The toxicity of cadmium, zinc, and cadmium/zinc mixtures at concentrations ranging from 10000 to 10 microg/l was investigated. Metal mixture toxicity investigation was undertaken with equal concentrations of the metals. The hatching of miracidia from eggs was inhibited by concentrations of 1000-10000 microg/l of single metals. Metal mixtures had no effect on egg hatching. Survival of miracidia was reduced by increasing metal concentration except at concentrations of 10 microg/l for single metal toxicity where survival was increased above the control. Miracidia demonstrated a rapid avoidance behaviour when briefly exposed to heavy metals. The mechanisms of metal toxicity to miracidia are briefly discussed.

Animals↗
PubMed2001

Toxicity of cadmium and zinc to encystment and in vitro excystment of Parorchis acanthus (Digenea: Philophthalmidae).

The toxicity of cadmium, zinc and cadmium/zinc mixtures at concentrations ranging from 1000 to 50000 microg/l were investigated against cercariae and metacercariae of Parorchis acanthus obtained from the dog whelk Nucella lapillus. Cercarial encystment at concentrations of 25000 microg/l or higher was significantly impaired by all test metals; however, at lower concentrations only zinc demonstrated toxicity. Mixtures of cadmium and zinc had a synergistic effect compared with single metal toxicity but only at 50000 microg/l. Excystment in vitro was only significantly affected by cercariae exposed to cadmium/zinc mixtures whilst encysting. Twenty-four h exposures of fully formed cysts had no effect on excystment in vitro. Effects on in vitro excystment rates over a 2 h period demonstrated widespread effects for cercariae-exposed P. acanthus. No effects were evident on excystment rates of cyst-exposed parasites.

Animals↗
PubMed2001

The responsibility to care for single homeless people.

This paper examines the reasons why in contemporary Britain many single homeless people with severe physical and mental health problems and welfare needs do not receive the treatment, care and financial support that they manifestly need, and in particular considers the interaction between their personal characteristics and the organisation and the obligations of services. Homelessness is a complex concept associated with problems of housing, health, social care and income. The greatest weaknesses of the service system are that no single agency has a statutory responsibility to ensure that vulnerable homeless people are served, and none of the generalist welfare agencies have a duty to seek out those who do not present. As a result, single homeless people fall between the housing, health and social services and amass exceptional unmet needs. The paper appraises the approaches to single homeless people's problems that have recently been introduced by the Rough Sleepers' Unit (RSU), and discusses the ways in which current reforms of the welfare services may impact on the situation of homeless people. With the possibility that the RSU's prime responsibility for commissioning single homeless people's services will transfer to local authorities in 2002, the paper concludes by specifying the implications for voluntary and statutory providers and makes recommendations about the attribution of the responsibility to care for this vulnerable group.

Aged↗
PubMed2001

Primary health care services for single homeless people: defects and opportunities.

BACKGROUND: An innovative residential centre in west London during 1997-1998 helped older rough sleepers leave the streets and resettle in conventional homes. Many clients presented with multiple physical illnesses complicated by chronicity and poor management. The centre initially experienced difficulties in obtaining health care for the residents, briefly relied on an A&E department for treatment of serious and minor ailments, and latterly was served by a GP practice supported by special funding. OBJECTIVE: The aims of this study were to describe the problems of providing at short notice primary health care services to a high-need group, and the prospective opportunities for the delivery of the required care. METHOD: A monitoring study collected routine operational data, life histories from 88 residents using a semi-structured questionnaire and information from 61 residents about their contacts with GPs before residence in the centre. Interviews were also conducted with the centre's staff, a Health Authority officer and a GP who treated the residents. RESULTS: The medical care of the residents was a major concern. Many had physical illnesses yet three-fifths had not seen a GP for more than 5 years. Many were not registered, even among those who recently had become homeless. It was difficult to organize the residents' medical care and to access special funding at short notice. When funding was secured, there were difficulties in contracting the service. CONCLUSION: Current registration and commissioning procedures are ill fitted to provide primary care services to a high-needs group at short notice. Primary Care Groups, special funding and contractual arrangements provide opportunities for GPs and primary health care workers to provide an improved service to marginalized and special needs groups. The responsibility to identify and respond to exceptional needs should be clearly defined and allocated.

Activities of Daily Living↗
PubMed2001

Detection and confirmation of reptilian adenovirus infection by in situ hybridization.

Adenovirus infections are documented in at least 12 different species of reptiles. In contrast to their mammalian and avian counterparts reptilian adenoviruses are not well characterized as to their pathogenic potential and their ability to cause primary disease. In the diagnostic setting, fresh tissues are often not available for virus isolation, and the confirmation of reptilian adenovirus infections is dependent largely upon electron microscopy for the identification of intranuclear viral inclusions associated with histopathologic changes. The diagnosis of adenovirus infection in 2 different species of snake was confirmed by the application of DNA in situ hybridization. Using an aviadenovirus specific oligoprobe, adenoviral DNA was observed in the nuclei of hepatocytes, Kupffer cells, endothelial cells, and enterocytes. Electron microscopy of the liver confirmed the presence of intranuclear viral particles morphologically consistent with an adenovirus. DNA in situ hybridization on formalin-fixed tissues can serve as a suitable alternative to electron microscopy in the diagnosis of reptilian adenovirus infections. Both affected snakes had other concurrent diseases, suggesting that the adenovirus may not have been the primary pathogen.

Adenoviridae↗
PubMed2001

IL-12, TNF-alpha, and hormonal changes during late pregnancy and early postpartum: implications for autoimmune disease activity during these times.

Clinical observations indicate that some autoimmune diseases, such as rheumatoid arthritis and multiple sclerosis, frequently remit during pregnancy but exacerbate, or have their onset, in the postpartum period. The immune basis for these phenomena is poorly understood. Recently, excessive production of IL-12 and TNF-alpha was causally linked to rheumatoid arthritis and multiple sclerosis. We studied 18 women with normal pregnancies in their third trimester and during the early postpartum period. We report that during the third trimester pregnancy, ex vivo monocytic IL-12 production was about 3-fold and TNF-alpha production was approximately 40% lower than postpartum values. At the same time, urinary cortisol and norepinephrine excretion and serum levels of 1,25-dihydroxyvitamin were 2- to 3-fold higher than postpartum values. As shown previously, these hormones can directly suppress IL-12 and TNF-alpha production by monocytes/macrophages in vitro. We suggest that a cortisol-, norepinephrine-, and 1,25-dihydroxyvitamin-induced inhibition and subsequent rebound of IL-12 and TNF-alpha production may represent a major mechanism by which pregnancy and postpartum alter the course of or susceptibility to various autoimmune disorders.

Adult↗
PubMed2001

Variability in acetylcholinesterase and glutathione S-transferase activities in Chironomus riparius Meigen deployed in situ at uncontaminated field sites.

An in situ system was used to expose fourth instar Chironomus riparius Meigen larvae for 48-h at 13 uncontaminated river sites across southeast England. Acetylcholinesterase (AChE) and glutathione S-transferase (GST) activities were measured in individual larvae recovered from these sites. Activities of both biomarkers varied almost twofold across the sites, with statistically significant differences detectable between sites. There were no clear relationships between biomarker activities and physical or chemical characteristics measured at each site. This study shows that biomarker measurements can be used successfully in conjunction with an in situ system. However, the results of statistically significant biomarker results must be treated with caution because natural variability in responses can occur even in the absence of toxicant exposure.

Acetylcholinesterase↗
PubMed2001

Abnormalities in sexual development of the amphipod Gammarus pulex (L.) found below sewage treatment works.

Increasing numbers of widely used industrial, agricultural, and natural chemicals are known to elicit endocrine-disrupting effects in a wide range of vertebrate and invertebrate species. The objective of this study was to determine whether the sexual development of the freshwater crustacean Gammarus pulex (L.) was affected below sewage treatment works (STW) previously known to contain endocrine-disrupting chemicals in their effluent. The gonadal structure, external sexual characteristics, and size of gammarids from exposed sites were compared to those of gammarids from a reference site. No significant difference was found in the gonadal structure of males collected below two STW. However, a highly significant number of females collected from a site known to elicit high estrogenic responses in vertebrates displayed an abnormal structure of oocytes in vitellogenesis. Body size was significantly shorter and male/female size differential was significantly reduced below one of the STW. Analysis of gnathopod and genital papillae length data suggests that different allometric relationships of these organs to body size exist between sample sites.

Animals↗